1.2.2 Update Release: Variable equations

Hey all!

Just a small update for Twine to Ren'Py 1.2.2:

• Supports variable equations in Twine with Ren'Py equivalent
  • Known bug: Any "$" will be removed from the statement (such a strings). Still figuring out how to solve this but I believe it's worth working around for the ability to support equations for now. Will update if I can find some consistent and reliable rules to determine one from another, but it'll likely be piecemeal.